Led by University of California, San Francisco professor Dr. Andrew D. Auerbach, the researchers found the connection between SSRIs and increased risks after scouring more than 530,000 medical records of US patients who underwent surgery at 375 hospitals between 2006 and 2008.

“There have been small studies that suggested there was a problem, but it has never been well-proven,” Auerbach said. “With this huge data set, we feel confident in saying that SSRIs are associated with about a 10 percent increased risk for these adverse outcomes.”

Because patients who have experienced symptoms of depression may also be overweight or have cardiopulmonary disease, the research team compared patients who had taken SSRIs with similar patients who were not taking the drugs. This allowed the team to control for variables such as age, gender, and weight. They found patients on SSRIs still were at increased risk.

The scientists also looked to see if patients had just received SSRI prescriptions before surgery, potentially using them incorrectly or at higher doses.

“This was not the case,” said Auerbach. “These drugs are almost never used acutely. They are prescribed for chronic conditions such as depression, almost always for long-term use.”

The researchers acknowledged their study was not designed to look at the cause behind the increased level of risk. However, Auerbach noted a side effect of SSRIs is the interference in the activity of platelets, which are mainly responsible for blood clotting. If platelets are sufficiently disrupted, it can lead to excess bleeding.

Because the new study was a research review, Auerbach suggested, “a prospective observational study, in which patients are randomly assigned to take SSRIs around the time of surgery, is still needed.”

However, in the study the authors note a comprehensive study would be a massive logistical and financial undertaking.

“Such a study would be quite costly, but given the ubiquitous nature of SSRIs in US health care and the potential risks of proceeding without adequate evidence for a strategy on how to mitigate risks of perioperative SSRI use, any study costs would seem money well spent,” they write.

Auerbach added it would be premature to advise patients to refrain from taking SSRIs before surgery, “it’s definitely worth discussing with your surgeon or primary care physician.”

Most mental health experts recommend against suddenly stopping an SSRI regimen as doing so can result in severe and debilitating psychological consequences. For those looking to unwind their SSRI regimen, experts suggest a gradually lessening of the daily or bi-daily dosage over the course of months.

Despite their benefits, SSRIs have been linked to other troubling side effects or complications, including sexual dysfunction, dizziness or suicidal thoughts. Doctors recommend the drugs be taken in conjunction with treatment from a mental health professional.